The present invention relates to a conveying apparatus suitable for conveying a number of coated car bodies or other loads supported on pallets in a drying furnace or the like.
Known conveying apparatus include a drying furnace through which loads successively pass and is installed between two conveying paths and positioned at a level higher than the paths. The inlet and outlet of the drying furnace are each provided with a lifting section for lifting and lowering the loads. This makes it possible to position the furnace inlet and outlet at a lower level in order to prevent heat from escaping out of the furnace through the inlet or outlet. Consequently, the thermal efficiency of the furnace can be higher. Such a drying furnace may be incorporated in a conveying line for conveying a number of loads on pallets supported and conveyed by a roller conveyor or the like. In this case, the inlet and outlet of the drying furnace need to be provided with large lifters for lifting and lowering the pallets. However, this results in enlargement of the apparatus and a great increase of the installation cost. Additionally, depending on the capacity of the lifters, it may be necessary to lengthen the time intervals at which the loads are conveyed into the drying furnace. This affects the overall cycle time.
The object of the present invention is to provide a conveying apparatus that can solve the foregoing problems with the prior art.
According to the present invention, there is provided a conveying apparatus for conveying a pallet in a predetermined direction. The conveying apparatus comprises a specific conveying path, a return path, an endless circulating driver and a number of pallet supporting and driving means. The conveying path includes a horizontal inlet path section, a horizontal outlet path section, and an inclined path section connected to at least one of the inner ends of the inlet and outlet path sections. The circulating driver circulates between the conveying and return paths. The supporting and driving means are mounted at intervals on the circulating driver. Each of the pallet supporting and driving means includes a front pallet support for supporting a front portion of the pallet, a rear pallet support for supporting a rear portion of the pallet, and a driving engager for automatically engaging with the pallet near the front pallet support. The pallet includes a front supported part that can be supported by the front pallet support, a rear supported part that can be supported by the rear pallet support movable relative to the pallet in the predetermined direction, and an engaged part for automatically engaging with the driving engager. The pallet conveyed to the inlet path section can be transferred onto one of the supporting and driving means, which conveys the pallet on it along the conveying path to the outlet path section.
A load can be carried on the pallet, which may be supported and conveyed by a roller conveyor. By merely transferring the pallet to the horizontal inlet path section by a suitable means, it is possible to support the pallet on the pallet supporting and driving means, and convey the supported pallet along the inclined path section into a conveying path connected to the inclined path section and positioned at a different level. In other words, a common conveying means conveys the pallet along the inclined path section and the conveying path at the different level. This removes the need to provide an exclusive lifter or the like for lifting or lowering the pallet. Consequently, the cost for the installation may be greatly reduced. Additionally, the apparatus is easy to control. Pallets can be conveyed successively into the conveying path at the different level. As a result, the work cycle time can be greatly shortened.
The conveying apparatus may further comprise two roller conveyors each provided in one of the horizontal inlet and outlet path sections. The roller conveyors may each include a pair of right and left roller rails for supporting both sides of the pallet. The pallet may include a pair of side frames that can be supported by the roller rails, a cross frame extending as both of the front supported part and the engaged part between the side frames, and a pair of right and left longitudinal frames extending as the rear supported part in the predetermined direction between the side frames.
The roller rails can support the pallet in the horizontal inlet and outlet path sections. This makes it easy to transfer the pallet to the inlet path section and from the outlet path section. More specifically, the roller rails can support the side frames of the pallet. The cross frame, which connects the side frames, can function both as the front supported part that can be supported by the front pallet support, and as the engaged part that can engage with the driving engager. This enables the pallet to be simple in structure with only the longitudinal frames added as the rear supported part that can be supported by the rear pallet support.
The front and rear pallet supports may each include a pair of right and left horizontal-axis rollers, each of which includes a flange. The front and rear supported parts of the pallet may have grooves for loosely engaging with the flanges of the rollers.
The roller flanges can engage with the pallet grooves to laterally position the pallet supported and conveyed by the pallet supporting and driving means. Consequently, without a special positioner provided, the pallet can be conveyed safely without laterally deviating.
The driving engager may include a pair of front and rear self-locking pawls for engaging with the front and rear sides respectively of the engaged part of the pallet. The pawls can tilt toward each other. In one embodiment, the pawls can only tilt toward each other. The engager may also include urging means urging the pawls into an erect position.
This structure makes it possible to convey the pallet reliably and safely at a predetermined speed in the predetermined direction, not only at the horizontal path sections, but also along the inclined path section, which may be either an up-grade path section or a down-grade path section.
The endless circulating driver may include a pair of right and left driving chains and a pair of guide rails each supporting and guiding one of the driving chains. The circulating driver may also include a front connecting member and a rear connecting member, which may be spaced from the front connecting member in the predetermined direction. The connecting members connect the driving chains together. The circulating driver may further include a front supporting frame and a rear supporting frame. The front supporting frame stands on the front connecting member and supports the front pallet support and the driving engager. The rear supporting frame stands on the rear connecting member and supports the rear pallet support.
This structure makes it possible to inexpensively produce a conveying apparatus that can be effectively used to convey large pallets.